Release block or cancel block objc - objective-c

Question

Am using a Class to make all the network calls to fetch data.
// Helper Class method for network calls
- (void) dataForUser:user withCompletionHandler:(void(^)(id response)) onComplete {
[[webClient sharedObject] fetchDataForUser:user withCompletionHandler:(void(^)(id response)) onComplete {
// do something to get data
onComplete(data);
}];
}
// View Controller's Model Class
- (void) getDataWithCompletionHandler:(void(^)(id)) onComplete {
// helperClassObj is a class variable
[helperClassObj dataForUser:userInfo withCompletionHandler:^(id response) {
// process response and store it as response 1.
onComplete(response1);
}];
}
I cannot make another request until one gets completed. How can I cancel a previous request so that I dont have to wait until I get data. Like I requested data for user1 and request for data for user2 and I need to display user2 data and be able to cancel the previous call.

Answer 1

// Helper Class method for network calls
- (void) dataForUser:user withCompletionHandler:(void(^)(id response)) onComplete {
[webClient fetchDataForUser:user withCompletionHandler:^(id response) {
// do something to get data
if(onComplete) {
onComplete(data);
}
}];
}
// View Controller's Model Class
BOOL isLastRequestCancelled = NO;
- (void) getDataWithCompletionHandler:(void(^)(id)) onComplete {
isLastRequestCancelled = YES;
// helperClassObj is a class variable
[helperClassObj dataForUser:userInfo withCompletionHandler:^(id response) {
// process response and store it as response1
if(!isLastRequestCancelled) {
if(onComplete) {
onComplete(response1);
}
}
isLastRequestCancelled = NO;
}];
}